Filling for thermal cut-outs.



No. 867,543. PATENTED OCT. 1, 1907. .F. H. WESTON. FILLING FOR THERMAL CUT-OUTS.

APPLIUATION FILED APR. 22, 1905.

Witnesses: Inventor:

. an absorbent or condenser, has acted as a packing or tamping action, there have been numerous instances To all whom it may concern:

vented certain new and useful Improvements in Fill- UNITED STATES PATENT OFFICE.

FREDERICK H. WESTON, OF SQHENEC'IADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

FILLING FOR THERMAL CUT-OUTS.

Specification of Letters Patent.

Patented Oct. 1, 1907.

Application filed April 22,1905; Serial No. 256,989

Be it known that I, FREDERICK H. WESTON, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have inings for Thermal Cut-Outs, of which the following is a specification.

The present invention relates to electric. cut-outs, and more particularly to the thermal type of such devices in which a strip of metal is provided which becomes severed by melting or volatilization upon the pe of an abnormal electric current.

It has been customary, in order to reduce the shock produced by the sudden volatilization and the scattering of masses of molten metal upon the disruption of a thermal cut-out to inclose it in an insulating casing of considerably larger diameter than the fusible strip and fill the unoccupied space with some finely divided or powdered insulating substance, which tends to condense the volatile gases and cool off the particles of molten metal, but wherethese prior cut-out devices were required to interrupt circuits carrying currents of considerable volume, their action has been unsatisfactory on account of the inability of the large volume of volatile gas to readily penetrate the interstices of the filling material, so that the latter, instead of acting as tamping for the suddenly evolved gases, and serving to aggravate the explosive action, rather than otherwise. Moreover, where refractory vitreous substances have been used in a coarsely divided state to avoid this of failure of the cut-out due to the flux ing effect of the current upon the filling material, especially under gradual overloads by which the filling isrendered conductive upon becoming heated, so that the current continues to flow after the disruption of the fusible member.

The object of my invention is to provide an absorbent material for thermal cut'outs which will effectually operate to extinguish the electric arc under all conditions of over-load and short-circuit, and reduce to a minimum the shock incident to the sudden volatiliza- .tion of the fusible member.

In the accompanying drawing Figure 1 shows in partial section an ordinary cartridge fuse with my improved filling material therein; and Fig. 2 is a similar view after the fuse has blown showing the filling discolored throughout.

The insulating shell I is closed at both ends by metallic thimbles 2 through which extend the contact blades 3 which are secured at the inner sides thereof to transverse yokes 4, and the thimbles and yokes are se- 1 cured to the shell by means of screws 5 passing through the flanges of the thimbles, the walls of the shell and entering tapped holes in the ends of the yokes in a well known manner. The ends of the fuse casing are packed with a fibrous material 6 such as asbestos, and the space about the fusible member 7 is filled with any absorbent material '8 consisting of small balls of refractory substance.

I employ a highly infusible substance which is reduced to a powdered form and ordinarily mixed with some suitable binder and madeinto granules or pellets. I have obtained excellent results from a filling of pellets made as follows: about 75 to 95 parts of slaked lime mixed with 5 to 25 parts of calcium sulfate, reduced to a powdered form and sufficient water added to form a batter. This batter is stirred until it stiffens sufficiently to crumble when pressed between the fingers, and is then passed through sieves of desired mesh to subdivide it into granules or pellets of substantially uniform size. The pellets are finally subjected to a drying process to drive off moisture. The pellets thus formed are hard, infusible and porous, incapable of being rendered conductive by heat, and when placed in quantity about a fusible strip a multitude of nonclogging channels are formed through which the volatile gases may readily distribute themselves upon blowing of the fuse, so that the pellets farthest removed from the fusible member are enabled to act with substantially the same absorptive effect upon the gases as the pellets in contact therewith, and in case the fuse becomes melted, on overload, the molten metal is not held in its original channel through the filling, as where the filling is in powdered form, but instantly runs out into the lowermost channels between the pellets and at once breaks the circuit.

I do not desire to limit myself to the particular ingredients or proportions herein set forth, since it is apparent that they may be replaced by others and combined in different proportions without departing from my invention.

What I claim as new, and desire to secure by Letters Patent of the United States, is,- 

